Safety valve for pneumatic tires



` Nov. Z 1926.

H, C. BOLL SAFETY VALVE Eon PNEUMATIG TIRES Filed March 6, 1925 im... I i

. UNITED ESTATE-s-,eATENT OFFICE.'

` HENRY o. Bonner NORTHY LITTLE Rooxfanmsas.

SAFETY VALVE Fon PNEUMATIoaIREsi.

Application filed March 6, 1925. -Serial No 13,434.

My invtionrelates to improvements in i safety valves for pneumatic tires, and has `t'or its preliminary object a safety valve which will release excess pressure from a pneumatic tire and prevent blowouts, it being a well-known fact that the pressure 1n pneumatic tires rises considerably when'the tire is rolled over a pavement, and 1t 1s to prevent this excessive pressure Iand consequent danger of blow-outs, while the vehicle is traveling, that my device is designed.

A further object is 'to construct a safety valve for pneumatic tires which can be set for any'predetermined pressure so that in the event too much air is introduced into the tire that same will escape. In other words,

when my` device has been once set, it will be impossible to over-inflate a tlre.

' ln the drawings y Fig.' l is a vertical section of my device showing the same applied to the upper part ot a valve stem. Y

Fig. 2 is a horizontal the line 2-2 of Fig. 1;

Fig. 3 is an enlarged vertical sectiony ofv the upper'portion ot a valve stem with my device incorpora-ted therein;` and Fig. 4 is a top plan view on a reduced scale of the valve stem shown in Fig. 3.

In the construction of my device I employ a valve stem 5, which is of ordinary construction and which hasits upper end provided with external screw threads and internal screw threads 7. Within the `valve stem 5 is located the ordinary valven inside 8f Secured to the valve stemby means of section` taken on .the screw threads 6 isa:cap;Qwhiclris provided with an upwardly'extending screw threaded portion 10. Intermediate the ends ofthe cap 9 -is a web 11, whichv is provided with a central depression 12, which is dev signed to contact vwith the stem 13 of the valve inside 8; the purposeof which will be explained in detail later. The depression 12 is provided with openings 14 so that air from'the tire can pass therethrough. A gasket 15 rests against the web to assist in making an air-tight joint. It will be noted from the drawings thatthe `screw threaded portion 10 is of smaller diameter so las to form a shoulder 16 on which a gasket 17 is placed. Secured to the screw threaded portion 10 of the cap 9 is a sleeve 18, which is' preferably screw threaded throughout its entire interior. Secured to the upper end ot the sleeve 18 is a cap 19, which is provided witlf1 ajsphericalidepression 20 and A gasket 2,2 is 'emwith a central bor'e21. ployed to assist-in making a leak-tight joint between the cap 19 and the sleeve 18;`cxi

tending through the bore2l is a stem 23, y, 'i' the lower end of which is made square as at '24. Fitting over the square portionl 24 of the stem 23 is a nut- 25, which is externally: screw threaded and which" is adapted to engage with Vthe screw threads formed in thel sleeve 18. The nut 25 tits the square por-)1,4 i tion loosely so as to permit an air passage,`

passage I may prointegral with the upper -end of the stem 23 is acup-shaped member 29, its upper end being preferably hexagonal so as to permit. turning of the stem. Surrounding the stem and located in the cup-shaped member 29 is a ball 30, which is preferably formed of rubber or similar .resilient material. The stem 23 is also provided with a longitudinally extending notch 31, which will permit the ready escape of air when the ball or valve 3() has been raised a predetermined distance out of the spherical recess or cup 20.

It is to be understood, of course, that the bore 21 through the cap 19 is slightly larger than the diameter of the stem 23 so that as soo-n as the valve 30 is unseated, air can bleed along the stem 23 and escape slowly.

In Fig. 3 I have shown a modified form in whichthe safety valve is incorporated directly in the valve stem. In this instance the valve stem 32 is provided 'with bores 33 and 34, which extend entirely through the stem. In the bore 33 is seated the usual valve inside 35. The valve stem is also provided with an externally screw threaded projection by means of which a valve cap 36 can be applied. lThe bore 34 is internal ly screw threaded so as to receive the safety valve. lfVith this construction it will be impossible to inflate a tire beyond the pres sure permitted by the safety valve as lall excess pressure will unseat the valve and per* mit the air to escape, thus permitting ,hat all l, the tire is irst inflated in'the ordinary' manner andas soon as '.the air. hose is removed the valve insdewll seat.. The-safety] valve is then screwed on over the "screw thread 6 and the central depression 12 of the cap 9 will unseat the valve inside. This will permit air from the tire to pass through.

the openings 14 and into the sleeve 18, and then up along the stem 23 until it is stopped by the valve 30.

Should any rise in pressure` occur within the tire due to the rise of temperature of the air, while the vehicle is moving, this excess pressure will lift the valve 30 and permit the air to escape until the desired pressure is reached, when the valve will again seat itself. The pressure at which the valve 30 unseats is regulated by turning the cap 29, which will cause the nut 25 to move up and down within the screw threaded sleeve 18,

thus increasing or decreasing the tension on the spring 28. In this of the valve 30 can be It is, of course, possible ning of a vehicle,

manner the unseating accurately regulated. that during the runeven should no rise in pressure take place, that a small percentage of air will escape when sudden jolts, such as hitting rocks and the like, are encountered, as this will naturally cause a momentary increase in pressure of the tire, but the amount of air thus escaping is so slight as-to be negligible; the loss thus being about the same as ordinarily will leak out through the ordinary valve. With the structure shown in Fig. 3, as previously described, it will be impossible to inflate a tire beyond its predetermined capacity or beyond the setting of the valve, because further influx of pressure will unseat the safety valve and' permit the air to escape. This will warn the person ini Hating the tire'that he has suflicient air therein and eliminates entirely the need of a pressure gauge.

My device can be either installed as shown in Fig. 1 to the present type of valve stem or, if desired, can be built directly in the stem, and when built in the stem, its dimension is changed in one direction only, so that the only changes necessary in the rim and Wheel y ill be to elongate the valve stem opening as the width of the stem will not be changed.

Having fully described my invention, what I claim is 1. A safety valve for pneumatic tires comprising an internally screw threaded memer, a cap provided with a depression carried by said member, a valve stem having a longitudinal groove extending through said cap, a nut located in said internally screw threaded member and rotatably carried by and slidably mounted on said valve stem,

. means for rotating said valve stem, a resilient member carried by said stem and normally seated in said depression for sealing said valve, and means for normally holding said resilient member in seated position.

2. A safety valve for pneumatic tires comprising an internally screw threaded sleeve, a cap provided with a depression carried by one end of said sleeve, a valve stem having a longitudinal groove extending through said cap, a nut provided with air passages and externally screw threaded located in said sleeve and rotatably carried by, and slidably mounted on said valve stem, a resilient member carried by said stem and located in said depression for sealing said valve, and means for normally holding said resilient member in seated position.

3. A safety valve for pneumatic tires comprising an internally screw threaded sleeve, a valve stem having a cylindrical upper portion and a square lower portion located in said sleeve and projecting beyond one end thereof, an externally screw threaded disk provided with air passages slidably mounted on said square portion, a second disk secured to the end of the square portion of said valve stem, a coil spring interposed between said disks and adapted to have it s tensionregu lated by the up and down'movement of the said screw threaded disk, a cap provided with a depression carried by the upper end of said sleeve and surrounding the valve stem, a resilient member carried by said valve stem and adapted to be held seated in said depression by said spring, and means for turning said valve stem sleeve whereby the tension of the spring is regulated and the pressure required to unseat the resilient member controlled.

In 'testimony whereof, I have signed my name to this specification.

HENRY C. BOLL.

for moving said screw threaded disk up and down in thev 

